Method of separating certain constituents from a gas or mixture of gases.



L. BRADLEY & w. A' scmvnm.

METHOD OF SEPARATING CERTAIN CONSTITUENTS FROM A GAS 0R MIXTURE 0FGASES.

APPLICATION FILED JULY 23, I914- Fig". .3.

Wl/E/I/TORS WIT/M58858:

Linn Bradley LINN IBRADLEY, OF EAST ORANGE, NEW JERSEY, AND WALTERAUGUST SCHMIDT, LOS ANGELES, CALIFORNIA, ASSIGNORS TO RESEARCHCORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHODOF SEPARATING CERTAIN CONSTITUEN TS FROM A GAS OR MIXTURE OFGASES.

1,221,5(l5. Specificati ers Patent Patented Apr. 3, 1917.

Application filed July 23, 1914. Serial No. 852,719.

To all whom it may concern:

tion of such chlorin it has been proposed to Be it known that we, LINNBRADLEY, re-l pass the gases through absorption towers or siding at EastOrange, county of Essex,- chambers containing hydrated calcium State ofN w J rsey, nd WALTER AUGUST oxid, the chlorin being absorbed by thecal- SoHMmT, residing at Los Angeles, county cium hydroxid. When largevolumes of of Los Angeles, State of California, citizens gases aretreated in this manner, difliculty is of the United States, haveinvented a new encountered in removing the last traces of and usefulMethod of Separating Certain chlorin, by reason of the difiicultyofbring- .60 Constituents from a Gas or Mixture of ing the gases intosufiiciently intimate con- Gases, of which the following is aspecificatact with the absorbent material. The funtion. damental purposeof our invention is to This invention relates to removing cerbring theabsorbent material quickly into tain gaseous constituents from a mixtureof intimate contact with the gases under treatgases or from a compoundgas and the main ment, and for continually renewing the abobject of theinvention is to provide for sorbing agent so that the absorption takessuch operation where the gas to be removed place with maximum rapidityand effectiveis not readily separable by condensation. ness. This objectwe accomplish by dis- The invention consists essentially in distributingthe absorbing agent throughout tributing into the gas 'or mixture ofgases the gas, in the form of a cloud of suspended to be treated, asolid pulverulent substance, particles, presenting maximum surface towhich is capable of reacting chemically or permit the absorption,thereby causingrapid physically with the constituents to besepaseparation of the desired constituent from rated from said gas ormixture of gases in the gaseous state. l/Ve then precipitate the suchmanner as to form a cloud, mist, or cloud of absorbing material,together with fume of suspended-particles, and in then the constituentabsorbed thereby from the removing such suspended particles from thegases. remainder of the gas. Our method is applicable to a wide range Inthe industries there are many cases of industrial and chemicalprocesses, and where it is desirable to remove from cerwhile it dependsfundamentally on the utitain gaseous bodies one constituent thereof,liza'tion of a cloud or mist of solid or liquid but where the removal ofsuch portion of particles in the gas under treatment, this the gasoffers serious difficulties in practice. cloud or mist may. be formed invarious This is particularly the case when the conways according to thespecial conditions of stituent to be removed cannot be condensed, theproblem. Thus, for example it may be su'blimed, or absorbed by the usualcomformed by spraying, forcing, or blowing mercial methods. In manycases the mixsolid particles into the gases, or otherwise,

ture of gases consists of permanent gases as hereinafterset forth. Wherecondensation or sublimation is en- Any suitable apparatus may be used intirely impracticable as a means of fractioncarrying out our method, forexample that ating or separating one constituent of the shown in the.accompanying drawings, a mixture from another, and where the usewherein: of ordinary absorption processes is objec: Figure 1 isathorizontal section of an aptionable, requiring large and expensiveabparatus suitable for the absorption of sorption means to furnish thenecessary surchlorin, by our method, from gases such as face andconditions for absorption of the occur in bleaching powder manufacture.gas-constituent. Ordinarily, difliculties are Fig. 2 is a verticalsection of the means encountered even with such provision in reforfeeding the absorbent material.

moving the desired constituent effectively Fig. 3 is a vertlcal sectionof the treater and with satisfactory completeness. Such difficulties aremet with, for example, in the removal of chlorin from a mixture ofgases, such as chlorin-laden air. For the absorpor precipitator.

Fig. 4 is a partly sectional side elevation of another form of apparatusfor carrying out our invention.

The apparatus shown in Fig.1 comprises" a flue or pipe 1 connected toreceive chlorinladen air from any source thereof, means for supplyinghydrated lime dus't (calcium hydroxid) to such flue or pipe, an electrictreater or precipitator 2, for precipitating the. dust after it hasabsorbed the chlorin, and a fan or blower 3 for drawing the chlorinladen air or gases through the-flue orpipe 1, and through the treater 2,and discharging the residual air'or gases through a stack or flue 4. Themeans for supplying the finely divided calcium hydroxid to the gasespassing through pipe or flue 1 may consist, for example, as shown, of afan or blower 6 having its intake pipe 7 connected to thepipe 1, andhaving an outlet pipe 8 connected-to said pipe 1 at a point in advanceof the treater 2, and means 9 for feeding the calcium hydroxid to theintake pipe,

said feeding means 9 consisting of an elenection with the manufacture'ofbleaching powder where the effluent gases, under usual practice atpresent, contain considerable chlorin, the chlorin is sufficientlydiffused as to necessarily demand that the absorbent material be soattenuated, that any of the usual precipitating means, such as settlingchambers, would be'ou't of the question, and it is only the extremerapidity and thoroughness'of action of the electric precipitator whichmakes the process practicable in such cases. A suitable form of electricprecipitator is shown in Figs. 1 and 3 and comprises a casing containingcollecting electrodes 13 and discharge electrodes 14, said casing beingconnected to receive the gases from pipe 1, and to discharge the gasesthrough pipe 1 to fan or blower 3. Means 5 are provided at the bottom ofthis casing for removing the precipitated material. The collectingelectrodes 13 areformed as plates or members presenting large surface,and the discharge electrodes 14 are formed as fine wires or equivalentmembers adapted, by reason of their small surface and their shape, tofacilitate discharge and produce ionizationof the gas, with resultantcharging of the particles suspended in the gas, these charged particlesbeing caused to precipitate upon the electrodes under the action of theelectric field between the electrodes. Discharge electrodes 14 may behung from insulated supports 20. Suitable electric connections areprovided for be connected by wire to a rectifier 17, which is connectedto receive and rectify alternating high tension current from ,atransformer 18. The collecting electrodes 13 may be grounded and therectifier 17 may be provided with ground connections to complete thecircuit. I

Our method is carried out in the above described apparatus as follows:Assuming that the method is to be applied to the recovery of the wastechlorin from the usual absorption towers or chamber in a bleachingpowder works, the chlorin laden gases from such towers or chambers aredrawn through the flue or pipe 1 by the action of the fan 3, and theabsorbing agent, namely the finely divided calcium hydroxid, is fed intothe intake pipe of fan 6, which draws such dust along with the currentof gases drawn through the pipe 8 by said fan and delivers the dust inthe form of a cloud of suspended particles into the flue 1.Thesesuspended particles become distributed throughout the .body ofgases in the flue 1, the length of said flue being suflicient to insurethat such distribution will take place before the gases reach thetreater 2, and that the particles of calcium hydroxid will be given fullopportunity to absorb the chlorin from the body of gases. The body ofgases drawn into the treater 2 from the flue or pipe- 1 containssuspended particles consisting, in general, of a mixture of calciumhydroxid and calcium oxychlorid, etc., the percentage portions ofchlorin and lime dust in the gases passing in the flue 1. In passingthrough the treater 2, the action of the electric discharge. causesionization of the gases, charging of the suspended particles, andprecipitation of such charged particles upon the electrodes. The productthereby precipitated on the electrodes falls, or is removed, intosuitable collecting means 5' at the bottom of the precipitator, whenceit may be removed in any suitable manner for example by screw conveyers.The gases, substantially free from chlorin, pass from the treaterthrough the fan 3 to the outlet 4, whence, being innocuous, they may bedischarged into the atmosphere. It is obvious that an impure calciumhydroxid could be injected in place of pure material, and that lime orhydrated lime charged with a certain amount of chlorin by this processor otherwise, could be injected into the chlorin laden gases, and thechlorin content of the product thereby increased. While the thoroughnessof separation of the chlorin by this process makes it advantageous inthe removal of the chlorin escaping from the usual of the latterdepending onthe relative protator 2 absorption towers or chambers, therapidity of action and large capacity of the method also makes itavailable for use independently of such towers or chambers, the chlorinladen gases being in that case delivered to the flue 1 directly from thesource thereof, and the chlorin being absorbed wholly by our improvedmethod. Thus by providing a plurality of dust feeders arranged atdifferent points along the flue, with a precipitator after each feeder,supplying fresh calcium hydroxid to the last feeder in the series,returning the partially charged precipitate resulting therefrom' to thenext preceding feeder, and in similar manner each feeder with thecharged product from the next succeeding feeder and precipitator, thechlorin content may be increased up to the limit of possible absorptionby the calcium hydroxid. An apparatus suitable for this purpose is shownin Fig. 4. A drying tower 25, containing, for example, quick-v lime, isprovided for drying the chlorinbearing gases, and temperaturecontrolling means 22, consisting,,for example, of a pipe for containinga cooling medium, is provided for maintaining the gases at the propertemperature during the operation. The cal cium hydroxid is taken fromsupply pit a, fed into the pipe 1 in advance of the last precipitator 2;the precipitate from the latter is conveyed by conveyer 5 to pit b,

whence it is fed to pipe 1, in advance of the first feeding and theresulting cloud of particles, containing an increased amount of chlorinis precipitated by precipitator 2*. Similarly the precipitate fromprecipitator 2 is conveyed to pit c and returned to pipe 1 and againtreated with fresh chlorin-bearing gas and the final precipitate, inprecipiis conveyed to pit d.

The means just described provides for control of the temperature so asto maintain the gas sufliciently cool for proper re action to take placewith the calcium hydroxid for producing bleaching powder of goodquality. It also provides for drying and purifying the gas, by theaction of the quicklime in removing moisture and CO and thereby aids inthe production of bleaching powder of good quality. Excessivetemperature due to reaction of the hydroxid and chlorin and the presenceof moisture and CO derived principally from the air mixed with thechlorin, tend to "seriously injure the quality of the bleaching powderproduced, and these objectionable actions are avoided by the operationsabove described. An important advantage of our process is that theaction of the electrical field produces violent agitation and relativemotion of the absorbent particles and the gas, 'so as to expedite andcomplete the absorbing action.

Another advantage of the use of our supplying treater is that thedeposited lime, on the plates, continues to absorb chlorin while thegases are passing between the plates, due

both to proximity of passing gas andto ele'c tric field causing electricwindage. For instance, a heavy deposit of dust can be placed upon thecollecting plates, and then chlorinladen gases introduced, even withoutcarrying suspended particles of hydrated lime, and the electric fieldwill accelerate the absorption of the chlorin by the previouslydeposited dust. The electrical windage also operates advantageously inagitating the gases and bringing them into effective contact with thesuspended particles. In man cases the ionizina action of the electricalfield may also be of direct advantage in promoting the chemical reactionbetween the absorbing agent and the gaseous constituent with which it isto react.

The absorbing material may operate by chemical combination with aconstituent of the gaseous body as in the above described instance, orit may absorb such constituent by physical action such as by solution,ab-

yea

sorption, occlusion, or otherwise, so that the cloud, fog or mist orfume of suspended particles carries the constituent or constituentswhich'are to be removed. In some cases the material injectedinto the gasin the form of a cloud may have a catalytic action upon the gas or on aconstituent thereof, producing products which are wholly or partlyabsorbed by such cloud, so that by precipitating the cloud, suchproducts are removed from the gas.

Among the many other applications of our invention in the industries thefollowing may be mentioned: the removal of moisture from the air passingto blast furnaces, by introducing a dehydrating agent, such aspulverized calcium chlorid, into such air and then precipitatingsuchagent, and in all such applications of our invention the precipitation of the cloud of particles by electric means is of advantagein that it enables particles of extreme fineness to be used, such ascould not be economically precipitated by the usual means.

Ourinvention may also be applied with advantage to the removal of tracesof gases, in a mixture of gases, as rapidly as they are formed, in suchreversible reactions as require very low concentration of the productsof reaction. As an illustration of this may be taken the directsynthesis of ammonia from nitrogen and hydrogen, where the equilibriumpoint of the reaction demands a very low concentration of the reactionproduct to permit of appreciable formation of ammonia. In this case,according to our invention, the gases will have intimately mixed withthem an absorbing agent such as phosphoric acid or boric acid which willabsorb the ammonia as rapidly as absorb the same and of forming a cloudor mist, and then precipitating such cloud or mist by subjecting the gasto the action of an electric field.

2. The method of separating a constituent from a gas or mixture ofgases, which consists in mixing with such gas or mixture of gases afinely divided non-gaseous material capable of absorbing suchconstituent and of forming a cloud or mist of suspended particlescontaining such constituent, and then precipitating such cloud or mistby subjecting the gas containing the cloud or mist to the action of anelectric field.

3. The method of separating a constituent from a gas or mixture ofgases, which con sistsin injecting into such gas or mixture of gases,dust or solid particles capable of reactin physically, to absorb thesame, and of forming a cloud or mist containing such constituent, andthen precipitating such cloud or mist by subjecting the gas containingsuch cloud or mist to the action of an electric field. v

4. The method of separating a gaseous constituent from a mixture ofgases which consists in injectin into such mixture, solid particlescapable 0 suspension in the gases and of absorbing such constituent andof forming a cloud or mist of suspended particles, and thenprecipitating said cloud or mist by subjecting the gas containing suchrjsiloilld or mist to the action of an electric e i 5. The 'method ofseparating a gaseous constituent from a mixture of gases, which consistsin injecting into such mixture, solid particles in such manner as toform a cloud or mist of particles containing said constituent, and thenprecipitating such cloud. or mist by subjecting the gas containing thecloud or mist to'the action of an electric field.

6. The method of separating a constituent from a gas or mixture of gaseswhich consistsin distributing in the gas or mixture of gases a finelydivided solid material capable of forming, with such constituent, acloud of suspended particles, and then passing the gas containing suchcloud through an electric with such constituent chemically or field inwhich an electric discharge is maintained, so as to precipitate saidcloud.

7. The method of separating a gaseous constituent from a mixture ofgases, which consists in injecting into such mixture, finely dividedsolid material, capable of absorbing such constituent, and of forming acloud of suspended particles, containing such constituent, and thenpassing the gas, containing such cloud, through an electric field inwhich an electric discharge is maintained, thereby precipitating suchcloud.

8. The method of separating a constituent from a gas or mixture ofgases, which consists in distributing in such gas or mixture of gases afinely divided solid material capable of reacting chemically orphysically with such constituent to form a cloud of suspended particles,containing such constituent, and then subjecting the gas containing suchcloud, to the action of an electricfield,

to precipitate such particles.

9. The method of separating a constituent from a gas or mixture ofgases, which consists in injecting into such gas or mixture of gases,dust or solid particles capable of reacting with such constituentchemically or physically, to absorb the same, and of forming a cloud ormist containing such constituent, and then precipitating such cloud ormist by subjecting the gas containing the cloud or mist to the action ofan electric field.

10. The method of separating a gaseous constituent from a mixture ofgases which consists in injecting into such mixture, solid particlescapable of suspension in the gases and of absorbing such constituent,and of forming a cloud or mist of suspended particles, and thenprecipitating said cloud or mist by subjecting the gas containing thecloud or mist to the action of an electric field.

11. The process of treating gases containing free chlorin, whichconsists in injecting into such gases, finely divided calcium hydroxid,to absorb the chlorin and to form a cloud of particles containing thechlorin together with the calcium hydroxid, and then precipitating thecloud of particles by the action of an electric field.

12. The process of treating gases containing free chlorin, whichconsists in distributing into the gas, finely divided calcium hydroxid,to absorb the chlorin and to form a cloud of particles containing thechlorin together with the calcium hydroxid, and then precipitating suchcloud of particles by the action of an electric field, the humidity ofthe gas being controlled to provide for efiective absorbing action.

13. The process of treating gases containing free chlorin, whichconsists in feeding and distributing into a current of the gas, finelydivided calcium hydroxid, precipitatadvance ing the resulting cloud ofparticles containing chlorin and calcium hydroxid, passing theprecipitate again into the gas current in of the first feeding, andprecipitating the resulting cloud of particles containing calciumhydroxid with an increased quantity of chlorin.

14. The process of absorbing a constituent from gases, which consists infeeding into a current of such gases, finely divided material capable ofabsorbing such constituent, precipitating the resulting cloud ofparticles, feeding such precipitate into said current in advance of thefirst feeding and precipitating the resulting cloud of finely dividedmaterial containing an increased amount of the gaseous constituent.

15. The process of producing chlorid of lime which consists in feedingcalcium hydroxid into a current of gas containing free chlorin,maintaining the gas at a temperature suitable for proper reaction of thechlorin and the calcium hydroxid so as to form a cloud ofsuspended'particles containing chlorid of lime, and precipitating suchcloud of suspended particles by the action of an electric field.

16. The process of absorbing a constituent from gases which consists insupplying and distributing particles of absorbent material in the gas,passing the gas between electrodes and maintaining a difference ofpotential between said electrodes to produce an' electric field ofsufiicient strength to precipitate the absorbent material and to causeelectric windage in contact with deposited material process ofseparating a constitumaterial-capable of absorbing such constituent, soas to form a. cloud of suspended particles and subjecting cloud ofsuspended particles to the action of the gas containin said anelectrical field and precipitating such par- 5 ticles with the gasconstituent absorbed thereby. A

18. The process f removing chlorin from a gas containing the same,consisting in distributing calcium hydroxid through such gas, in afinely divided state, to form a cloud and precipitating such cloud bythe action of an electrical field, the amount of calcium hydroxid usedbeing suflicient to effectively absorb and retain the chlorin in saidgas.

LINN BRADLEY. l WALTER AUGUST SCHMIDT.

